At present, with the rapid development of the WLAN, the application range of the WLAN is increasingly enlarged. In order to cope with various network requirements, the industrial standard IEEE802.11 Group of Institute of Electrical and Electronics Engineers (IEEE) issues a series of basic WLAN technical standards such as 802.11ah, 802.11b, 802.11g, 802.11n and the like, and then other task groups are established in succession to develop specifications involved in technical improvements of existing 802.11. For example, with the development of an Internet of Things, IEEE has set up an IEEE 802.11ah task group. A main task of the IEEE 802.11ah task group is to modify and enhance a Media Access Control (MAC) layer and a Physical (PHY) layer of the WLAN to accommodate requirements for networks such as a Smart Grid, an Environmental/Agricultural Monitoring network, an Industrial Process Automation network and the like.
In the WLAN, an Access Point (AP) and a plurality of non-AP Stations (STAs) associated with the AP constitute a Basic Service Set (BSS). An STA, before using a service of the BSS, has to complete authentication and association processes along with the AP. FIG. 1 is a flow chart where an STA accesses to an AP. As shown in FIG. 1, the process during which the STA accesses to the AP is as follows. The STA acquires a system information parameter of the BSS by sending a Probe Request frame and receiving a Probe Response frame to which the AP responds, or by receiving a Beacon frame broadcast by the AP. The STA sends an Authentication Request frame to the AP for authentication. The AP returns an Authentication Response frame to respond to the Authentication Request frame. The Authentication Response frame indicates whether the authentication is successful. After the authentication is completed, the STA proceeds to the association process. The STA sends an Association Request frame to the AP for association. The AP returns an Association Response frame to respond to the Association Request frame. The Association Response frame indicates whether the association is successful. If the association is successful, an Association Identifier (AID) is assigned to the STA in the Association Response frame. If the authentication and association processes are successful, the STA completes a basic access process.
A reassociation process is as follows. If the STA wishes to reassociate with the AP, the STA sends a Reassociation Request frame to the associated AP for reassociation. The AP returns a Reassociation Response frame to respond to the Reassociation Request frame. The Reassociation Response frame in which a new AID reassigned to the STA is included indicates whether the reassociation is successful. After the reassociation is completed, the STA can transfer data along with the AP by using the new AID.
In a new WLAN application scenario, it is required that the AP can support up to 6000 STAs. So many STAs also raise many new problems for the network. The first problem is that there are no enough station identifiers available for assignment in the network. For example, there are 1 to 2007 available AIDs in a WLAN system. Each STA of these identifiers cannot be identified one by one when the number of the STAs exceeds 2007. Secondly, more effective network management is needed when there are many stations. However, in a practical application, different STAs may have different application categories (such as an intelligent water meter, an intelligent ammeter, an intelligent gas meter), which belong to different manufacturer operation managements respectively and also require different power saving capabilities. But in the existing WLAN protocol, when the AP assigns the identifiers, the AP does not distinguish the STAs according to the characteristics of the STAs, namely, the AP does not group the STAs.
When there are a large number of STAs in the network and the characteristics of these STAs are different each other, there are problems of no enough assignable AIDs, lack of effective station grouping management and the like.